Slurry catalyst compositions, means for their preparation and their use in hydroprocessing of heavy feeds are known in the refining arts. Some examples are discussed below:
U.S. Pat. No. 4,710,486 discloses a process for the preparation of a dispersed Group VIB metal sulfide hydrocarbon oil hydroprocessing catalyst. Process steps include reacting aqueous ammonia and a Group VIB metal compound, such as molybdenum oxide or tungsten oxide, to form a water soluble oxygen-containing compound such as ammonium molybdate or tungstate.
U.S. Pat. No. 4,970,190 discloses a process for the preparation of a dispersed Group VIB metal sulfide catalyst for use in hydrocarbon oil hydroprocessing. This catalyst is promoted with a Group VIII Metal. Process steps include dissolving a Group VIB metal compound, such as molybdenum oxide or tungsten oxide, with ammonia to form a water soluble compound such as aqueous ammonium molybdate or ammonium tungstate.
Slurry hydroprocessing processes frequently operate at higher temperatures than those at which slurries comprising catalysts are synthesized and stored. For example, the slurry hydrocracking process of U.S. Publication No. 20060054533 typically operates at a temperature of at least 800° F., with a hydrogen pressure from about 1500 psi to about 3500 psi. The slurry catalysts generally enter the reactor (or initial reactor, if more than one) of the vacuum residuum hydroprocessing unit at a temperature around 450° F. and a hydrogen pressure of about 400 psi. This temperature and pressure differential shocks the highly active slurry catalyst and promotes the production of coke. Coke production decreases the efficiency of conversion by this catalyst.